Power actuator mechanism



April 13, 1965 Filed Jan. '7, 1963 INVENTOR. ROBERT MCLELLAND A-r-roRHeY f: ,en

April 13, 1965 R. MCCLELLAND 3,178,154

POWER ACTUATOR MECHANISM Filed Jan. 7, 1963 f 5 Sheecs-Shee'fl 2 01 INVENTOR esser MCLeLLAnb ATTORNEY pril 13, 1965 R. MccLELLAND POWER ACTUATOR MECHANISM 5 Sheets-Sheet 3 Filed Jan. 7, 1963 INVENTOR. ROBERT McCLaLLANn uw w. ma@

ATTQRNEY- April 13, 1965 R. MOcLr-:LLAND POWER ACTUATOR MECHANISM 5 Sheets-Sheet 4 Filed Jan. '7, 1963 .l Nd

INVENTOR ROBERT Wlc CLELLAND 21m zu. www

ATTORNEY pril 13, 1965 R. MGCLELLAND POWER AcTUAToR MEcHANIsM 5 Sheets-Sheet 5 INVENTOR BERT MCCLeLLANo Filed Jan. '7, 1963 UnitedStates Patent O 3,178,154 PWER ACTUATR MECHANISM Robert McClelland, Butler, Wis., assiguor to Safway Steel Products, Inc., Milwaukee, Wis., a corporation of Wisconsin Filed Jan. 7, 1963, Ser. No. 249,759 Claims. (Cl. 254-1) This invention relates to an improved push-pull actuator mechanism for operating bleachers and the like between an open and a nested position.

The principal object of this invention is to provide such a mechanism which is relatively simple and cornpact and which has a positively driven actuator chain which at all times moves parallel to the path of movement of the bleacher or other similar structure to be moved.

Other objects and advantages will be pointed out in, or be apparent from the specification and claims, as will obvious modifications of the single embodiment shown in the drawings, in which:

FIG. 1 is a side elevation View of a retractable bleacher (in nested position) equipped with the push-pull actuator mechanism of the present invention;

FIGS. 2 and 3 combined is a side elevation view of the retractable bleacher and actuator mechanism shown in FIG. l with the bleachers in open position;

FIG. 4 is a partially schematic plan view of a plurality of retractable bleacher sections equipped with actuator mechanism made in accordance with the present invention;

FIG. 5 is a fragmentary side elevation view of the actuator mechanism of this invention with parts broken away;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 5;

FIG. 7 is a horizontal sectional view taken along line 7-7 of FIG. 5;

FIG. 8 is a vertical sectional View taken along line 8 8 of FIG. 7; and

FIG. 9 is a vertical sectional view taken along line 9--9 ofFIG. 8.

Referring now to the drawings, FIGS. 1, 2 and 3 show a vretractable bleacher section 10 of the type which can be nested together when not in use as shown in FIG. 1 and opened to useable position when desired to the position shown in combined FIGS. 2`and 3. The push-pull actuator mechanism 12 of this invention may be employed with retractable bleachers of various design and since the specific construct-ion of the bleacher section 10 shown in tre drawings is not a part of this invention, such construction will not be described in detail herein. Broadly speaking, each bleacher section 10 is comprised of seat assemblies 14 of graduated height movably mounted on rollers 16 and adapted to nest one inside the other when in retracted position (FIG. l).

As shown in FIG. 4, a single actuator mechanism 12 may be employed to operate a bleacher unit comprising two (or more) complete bleacher section 10. Both actuators 12 (FIG. 4) are driven by a reversible electric motor drive unit 18 operatively connected to the actuator mechanisms by drive shaft sections 20 and 22. As shown in FIG. 4, actuators 12 and motor drive unit 18 are mounted beneath the bleacher units up against a wall 24 from which the bleachers areretracted for use. While motor drive 18 is shown driving a pair of actuators 12 each of which operates a pair of bleacher sections 10, it should be understood that by the use of drive shaft extensions 26and 28 a single drive motor can be employed to drive additional actuators each of which operates an additional pair of bleacher sections.

Referring now to the specific construction and operae ICC tion of the push-pull actuator mechanism 12 of this invention, as shown in FIGS. 5-9, such mechanism is comprised of an actuator chain 3Q, a storage rack 32 for the chain, and a positive drive assembly 34 for driving the chain.

Chain 30 is comprised of pairs of link members 36 andV 38 pivotally connected together to form a chain by means of shaft members 40 which also serve as axles for chain support rollers 42. Chain 30 is secured to the front seat assembly 14 of bleacher section 10 by any suitable means such as that shown in FIG. l wherein pins 44 and nuts 46 are utilized permitting easy adjustment of the length of chain 30 for the purpose of synchronizing one or more push chains for proper alignment of the bleacher sections. As shown in FIG. 7, link members 36 and 38 are oiset as at 48 so that the leading ends of each pair of links will lit inside in overlapping engagement with the trailing ends 52 of each successive pair of links. Shaft members 40 pass through the overlapped portions of adjacent links to pivotally connect such links together.

A cross bar member 54 is fastened between the trailing ends 52 of each pair of links by welding or other suitable means as shown in FIG. 7. The cross bars perform several important functions. First it is noted that they are fastened to end portions 52 in the area where such end portions overlap with the leading end portions 50 of the next adjacent link. Thus, bars S4 serve as stop members to prevent any pivotal movement between adjacent links which would tend to cause buckling of the chain upwardly from the door when the chain is performing its pushing function. Since the floor restrains al1 downward forces and bars $4 restrain all upward forces when the chain is in operative position (on the floor), the chain in etfect becomes a substantially rigid member capable of exerting the necessary force on the front portion of a bleacher unit to push such unit all the way out to its completely open position.

As clearly shown -in FIG. 9, cross bars 54 are provided with downwardly oifset portions 56 which cooperate with chain drive assembly 34 to drive the actuator chain in and out as will presently be described.

As shown in FIG. 8, chain drive assembly 34 is comprised of a drive chain 58 mounted on a pair of horizontally spaced sprockets 61 and 62. Chain 58 is provided with a plurality of equally spaced drive bar members 60 which extend transversely of the chain on opposite sides Y thereof. Bars 60 may be fastened to chain 58 in any suitable manner such as that shown in FIG. 7 wherein each bar is made integral with every other connecting link member 64 of chain 5S. Chain 5S is mounted so that during a portion of its travel it will move adjacent to and parallel with actuator chain 30 over the center line thereof so that drive chain 58 will become drivingly engaged with the actuator chain as drive bars 60 engage offset portions 56 of actuator chain cross bars 54. As shown in FIG. 9, by offsetting portions 56 of cross bars 54 downwardly and positioning drive chain 58 on top of the actuator chain, offset portions 56 together form a trough-like support for the chain drive to thereby insure a very effective driving connection between the two chains wherein the 'driving force of drive cha-in 58 is applied to the actuator chain 39 at the most desirable location, i.e. at or near the center of gravity of the actuator chain. Drive bar members 60, it is noted, are located on the center line of drive chain 58. This relationship provides minimum wear and power loss as the two chains move in and out of engagement.

Drive chain 5S is driven by motor unit 1S through sprocket 61 which is keyed to drive shaft 20. It will be appreciated thatv actuator chain 30 can be driven in either direction by simply reversing the direction of the drive 'B motor, the driving connection between drive chain 58 and actuator chain 30 being equally eiiective in either direct-ion.

As shown in FIGS. 1, 2 and 6, a unique arrangement is provided for storage of actuator chain 30 when retracting the bleachers to nested position. Such arrangement is comprised of a spirally shaped rack assembly 32 positioned at the rear of the bleachers and above the operating level of the actuator chain. Rack assembly 32 includes a pair of curved tracks 66, 66 which are positioned to receive rollers 42 and guide the actuator chain into the desired storage area. The rack further serves to house and protect the chain when the bleachers are retracted. The particular configuration of tracks 66 can be varied depending on the storage space available. In the preferred embodiment shown in the drawings the tracks are formed in an elongated vertically extended oval to thereby store the chain as close to the wall at the rear of the bleachers as possible. The tracks are spiraled inwardly to the extent necessary to receive the entire chain when completely retracted. By spiraling tracks 66 inwardly back over the operating path of the actuator chain as shown in FIG. 1, the chain links are pivot-ed on shaft members 40 in the only direction in which they are permitted to pivot by cross bars 54, as previously described.

It should be noted that by the use of the above described storage assembly, chain 30 can be fed in or out for operating a bleacher unit with the center line of the chain at all times lying in a common plane which extends parallel with the path of movement of the bleachers, i.e. with the chain at all times moving at right angles with the bleacher seats. This relationship serves to substantially eliminate sideways forces on the chain with the attendant detrimental effects on the overall operation of the actuator mechanism.

Briey stated, the actuator mechanism 12 operates as follows. Assume bleacher sections are in the nested position shown in FIG. 1. To open the bleachers, motor drive unit 18 is energized in the open direction causing drive shaft 20 to rotate sprocket 62 which, in turn, drives chain 58 in a clockwise direction as viewed in FIG. 8. When so driven drive bars 60 on chain 53 will engage olset portions 56 of cross bars 54 to thereby drive actuator chain to the left as shown in FIG. 8. The bleachers are `thus opened from the position shown in FIG. l to that shown in combined FIGS. 2 and 3. If it is desired to only partially open the bleachers motor unit 18 can be shut off at any desired point to thereby open the bleachers to any given number of rows. The actuator mechanism 12 can be arranged to shut oi automatically upon reaching either fully open or fully closed position by suitable limit switches (not shown). When it is desired to close the bleachers, motor unit 18 is simply energized in the reverse direction causing drive chain 58 to rotate counterclockwise (FIG. 8) and thus drive chairr 30 to the right into storage yrack 32. While the actuator mechanism of this invention, as shown and described herein, yis used to operate a retractable bleacher structure, it should be understood that such mechanism may be put to a variety of uses such as operating retractable chair risers, materials handling and storage equipment, etc.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

I claim:

1. A push-pull actuator mechanism for operating retractable bleachers and the like comprising:

an actuator chain means including an actuator chain adapted when actuated to open and close the retractable bleacher; and

a drive means for said actuator chain means including a drive chain overlying said actuator chain and adapted to travel parallel therewith, said actuator chain means and drive means including parts which assume a driving engagement with each other as said drive chain moves in parallel overlying relationship with said actuator chain, said parts including a cross bar fastened to said actuator chain and a drive bar fastened to said drive chain adapted for driving engagement with said cross bar. T2. A push-pull actuator mechanism according to claim 1 in which said cross bar has a downwardly oiset portion adapted yto receive and support said drive chain therein and further adapted for engagement by said drive bar on said drive chain.

3. A push-pull actuator mechanism for operating retractable bleachers and the like comprising:

an actuator chain means including an actuator chain adapted when actuated to open and close a retractable bleacher; a drive means for said actuator chain means including a drive member in driving engagement with said actuator chain, said drive member adapted to rotate in a common vertical plane with said actuator chain; and storage means for said actuator chain, said storage means including track means adapted to guide said actuator chain in a spiral path which extends upwardly and back over said actuator member with the center line of said actuator chain at all times remaining in a common plane which extends parallel to the path of movement of the bleachers, said actuator chain means including a plurality of cross bar member fastened to said actuator chain and said drive means 'including a plurality of drive bar members fastened to said drive member, said cross bar members and drive bar members adapted to assume a driving engagement with each other as such drive chain moves in parallel overlying relationship with said actuator chain. 4. A push-pull actuator mechanism according to claim 3 in which said cross bar members have downwardly olfset portions adapted to receive and support said drive chain therein and further adapted for engagement by said drive bar members on said drive chain.`

5. A push-pull actuator mechanism for operating retractable bleachers and the like comprising:

an actuator chain means including an actuator chain adapted when actuated to open and close a retractable bleacher; a drive means for said actuator chain means including a drive member operatively connected to said actuator chain; and storage means for said actuator chain, said storage means including track means adapted to guide said actuator chain in a spiral path which extends upwardly and back over said actuator member, said actuator chain, actuator member and track means all lying in a common vertical plane which extends parallel to the path of movement of the bleachers.

References Cited in the le of this patent UNITED STATES PATENTS 1,870,244 Elston Aug. 9, 1932 2,832,590 Youngberg Apr. 29, 1958 2,896,908 Stone July 28, 1959 FOREIGN PATENTS 483,652 Great Britain Apr. 2l, 1938 OTHER REFERENCES Wayne Iron Works pamphlet 23 j/ wa, No. 40 M 9312- 859-B 20-1.126, Gymnasium Seating Models 30, 50, and 70, copy received in Div. 33 Nov. 1, 1960 (8 pages). 

5. A PUSH-PULL ACTUATOR MECHANISM FOR OPERATING RETRACTABLE BLEACHERS AND THE LIKE COMPRISING: AN ACTUATOR CHAIN MEANS INCLUDING AN ACTUATOR CHAIN ADAPTED WHEN ACTUATED TO OPEN AN CLOSE A RETRACTABLE BLEACHER; A DRIVE MEANS FOR SAID ACTUATOR CHAIN MEANS INCLUDING A DRIVE MEMBER OPERATIVELY CONNECTED TO SAID ACTUATOR CHAIN; AND STORAGE MEANS FOR SAID ACTUATOR CHAIN, SAID STORAGE MEANS INCLUDING TRACK MEANS ADAPTED TO GUIDE SAID ACTUATOR CHAIN IN A SPIRAL PATH WHICH EXTENDS UPWARDLY AND BACK OVER SAID ACTUATOR MEMBER, SAID ACTUATOR CHAIN, ACTUATOR MEMBER AND TRACK MEANS ALL LYING IN A COMMON VERTICAL PLANE WHICH EXTENDS PARALLEL TO THE PATH OF MOVEMENT OF THE BLEACHERS. 